Mercapto-substituted hydroquinone developing agents



United States Patent Othce 3,542,554 Patented Nov. 24, 1970 Int. Cl.G03c 5/38 US. Cl. 96--61 13 Claims ABSTRACT OF THE DISCLOSURE Monobathscontaining certain mercapto-substituted hydroquinone developing agentsand mercaptan stabilizing agents for developing and stabilizingphotosensitive elements have improved stability and increased usefulprocessing life.

This invention relates to mercaptan monobath compositions and processesfor the development of silver images in photographic silver salt layersof photographic elements. In one of its aspects, the invention relatesto the use of mercaptan stabilized monobaths containing a hydroquinonesilver salt developing agent having at least one alkyl or aryl thioradical containing at least one water solubilizing group.

It is well known that developed silver salt layers of photographicelements containing silver images require the removal or inactivation ofthe residual unexposed silver salt for the image to be stable underadverse conditions of light, heat and humidity. For this reason, fixingand washing steps are ordinarily employed after development to convertthe silver halide to a soluble salt which is then washed from theemulsion layer.

A number of processes have been proposed to simplify or avoid the two ormore fixing and washing steps. In this connection, mercapto compoundshave been found to be good silver complexing agents. For example, US.Pat. 2,453,346 of Russell issued Nov. 9, 1948, discloses the use ofvarious sulfur compounds in conjunction with metal salts for stabilizingsilver prints. Acidic solutions containing the sulfur compounds andmetal salts are applied to silver halide emulsion layers followingdevelopment of the silver image. In US. Pat. 2,525,532 of Dreywood,issued Oct. 10, 1950, emulsion layers are developed with ap-methylaminophenol-hydroquinone developer solution containing varioussulfur compounds. Following development, the emulsions are treated withacid solutions prior to drying. In US. Pat. 2,614,927 of Broughton etal., issued Oct. 21, 1952, emulsions containing certain developingagents are processed with alkaline solutions followed by inactivation ofthe residual silver halide with solutions of sulfur compounds, such asthio glycolic acid, thiourea or thiosulfates.

Monobaths formed by the combination of developing agents with silvercomplexing agents have greatly simplitied the mechanics of processingphotographic films, papers, etc., by developing and fixing the exposedelement in a single solution. Monobaths are well known as described, forexample, in The Monobath Manual by Grant M. Haist, 1966. US. Pat.2,875,048 of Haist et al., issued Feb. 24, 1959, proposes a monobathcomposition comprising an alkaline solution of a hydroxylamine or3-pyrazolidone developing agent and a monothioglycerol, thioglycol,fi-mercaptoethylamine, N,N-diethyl-fimercaptoethylamine or2-thiobarbituric acid. While such mercaptan-containing monobaths areknown, when mercaptan monobaths contain hydroquinone as a developingagent they rapidly lose the silver complexing activity of the mercaptandue to aerial oxidation.

In this connection, it mercaptan compound stabilizers are used withunsubstituted hydroquinones in certain monobaths, there is rapidreaction between the two and stable monobaths cannot be prepared. Themonobaths and monobath processes of this invention overcome this problemwhile providing increased stability to oxidation with constantstabilizing activity without further addition of mercaptan stabilizers.

An object of the invention is, therefore, to provide means for producingstable silver images with mercaptancontaining monobaths which reduceloss in mercaptan complexing activity.

Another object of the invention is to provide a monobath processemploying a mercaptan silver complexing agent which process is resistantto loss in mercaptan silver complexing activity.

These and other objects will be apparent from the following description.

It was surprisingly found that by employing a mercaptan monobathcomposition and process wherein a mono bath containing (a) a mercaptansilver salt stabilizing agent,

(b) a hydroquinone silver salt developing agent having at least one SRYradical wherein R is alkylene or arylene and Y is a water solubilizinggroup, and

(c) a development activator,

for developing and fixing an image in an exposed photographic silversalt emulsion (a) there is no undesired reaction of the mercaptanstabilizing agent with the hydroquinone silver salt developing agent,

(b) the desired monobath has increased stability to oxidation and (c)has longer constant stabilizing activity Without further addition ofmercaptan stabilizing agent.

arylene and Y is a water solubilizing group, and (c) a developmentactivator.

Monobaths are well known in the art, as set out in the referencesdescribed. Monobath, as employed herein, means a composition containinga silver salt developing agent and a silver salt fixing or stabilizingagent. It usually refers to an aqueous solution of such developingagents and fixing or stabilizing agents. Monobaths within the scope ofthe invention effect both development and stabilization of the silversalt emulsion. Further definition of the term monobath is set out in.the book The Monobath Manual by Grant M. Haist, 1966.

A wide range of mercaptans can be employed in the monobaths of thisinvention as stabilizers for silver salts. Such mercaptan silver saltstabilizing agents can be any silver salt stabilizing agent mercaptancompound which is compatible with the components of the monobath andeffects the desired fixing and/or stabilization. Suitable silver saltstabilizing agents include, for instance, those represented by theformula:

wherein R is an alkylene or arylene radical and Y is a watersolubilizing group. Suitable alkylene or arylene groups include thosewhich are substituted, such as those which contain mercaptan, i.e. SH,hydroxyl, and car- 3 boxyl groups, as Well as any groups which do notadversely aifect the stabilizing or fixing action of the mercaptan. R istypically an alkylene or arylene radical containing 1 to 20 carbonatoms, e.g., methylene, ethylene, propylene, butylene, isobutylene,isopropylene, hydroxypropylene (-CH CHOHCH carboxyethylene (CHCOOHCHphenylene, naphthylene, and xylylene ('CH2C6H4CH2) A water solubilizinggroup as employed herein is one which (a) has the effect of making thecompound containing the group more soluble in water than thecorresponding compound Without the Water solubilizing group and (b) hasno substantial adverse affect on the stabilizing action of the mercaptanstabilizing agents or developing action of the developing agentsemployed in the practice of the invention. Such water solubilizinggroups include, for example, hydroxyl and carboxyl radicals.

Useful mercaptan silver salt stabilizing agents include for instance:

mercaptoethanol HSCH CH OH mercaptopropanol HSCH CH CH OH mercaptoaceticacid HSCH COOH fl-mercaptopropionic acid HSCH CH -COOH mercaptobenzoicacid HSC H COOH mereaptosuceinic acid 0 O OH di-mercaptoadipie acid 0 OO H C O O H a-mereaptopropionic acid i H S --CH0 0 OH Any suitableconcentration of mercaptan silver salt stabilizing agent can be employedin the monobath composition of the invention. An amount of about 1% toabout 50% by weight of the total monobath composition is usuallysuflicient. For example, Where the monobath is an aqueous solutionusually about 10 grams to about 500 grams of mercaptan silver saltstabilizing agent is sufiicient per liter of the total monobath.Concentrations outside this range can be employed.

The described hydroquinone silver salt developing agent can be anysilver salt developing agent, typically a silver halide developingagent, which (a) afiects development of the exposed silver salt withoutadversely aifecting the other desired properties of the monobath, e.g.,the desired stabilization action, (b) has a 1,4-dihydroxybenzenenucleus, and (c) has at least one SR-Y radical wherein R and Y are asdescribed herein with respect to the aforementioned mercaptans employedin the monobaths of the invention as stabilizers. Mixtures of suchdeveloping agents can also be used. The 1,4-dihydroxybenzene nucleus cancontain substituents in addition to the one or more S-RY radicals. Thesesubstituents can be any radical which does not adversely aifect thedesired action of the monobath. For example, suitable substituentsinclude hydroxyl, lower alkyl, e.g., methyl, ethyl, propyl, butyl,t-butyl and isopropyl, chloro or bromo radicals.

Any suitable amount of the described developing agent can be employed inthe practice of the invention. An amount of developing agent of about0.5% to about 10% wherein R is an alkylene or arylene radical containing1- to 20 carbon atoms and Y is a water solubilizing group.

Hydroquinone silver salt developing agents which can be employed in thepractice of the invention include:

-somc1non l on 2- 2,5-dihydroxyphenylthio ethanol 311 @somonomona-hydroxy-,8- (2, S-dihydroxyphenylthio propanol on -sonzcoon I OH2,S-dihydroxyphenylthioacetic acid on -s 011201120 0 01-1 I OH a 2,5-dihydroxyphenylthio propionic acid (III)a-(2,5-dihydroxyphenylthio)propionic acid (VI) OH I SCHCH2OOOH2,5-dihydroxyphenylthiosuccinic acid COOHo-(2,5-dihydroxyphenylthio)benzoic acid (VIII) OH I C O OH O O OH (VII)a- 2,5 -dihydroxyphenylthio -a'-mercaptoadipic acid (IX) OH OH I ('30 OHO OH I S CH H CS CHzC'Hz i I OH OH a,u'-Bis(2,5-dihydroxyphenythio)adipic acid Any development activator and any suitableconcentration of development activator can be employed in the monobathof the invention which provides the desired alkalinity or pH to elfectthe desired development. Typical development activators includeinorganic development activators such as sodium hydroxide, potassiumhydroxide and lithium hydroxide, as well as organic activators, such asorganic amines, e.g. ethanolamine, morpholine, propanolamine, and thelike. The pH of the monobath can vary over wide ranges, but in general apH of at least 9 is employed, e.g., preferably about 10.0 to about 13.

Additional inorganic salts can be present in the desired monobath. Theseinclude, for example:

Al (N0 3 9H O Bi (Cal-I90 Ce 3) 3 CsCl PdCl

RbCl

((321 1302) 3 H2O PdCl RbCl RhCl SH O SbCl Sc ah Srn(NO SnCl TiCl V50 7HO Y3 YbCl 6H O YnCl These inorganic compounds have also been foundeffective in aiding stabilization and extending the active life time ofother monobaths containing mercaptan stabilizing agents. Such monobathsare disclosed, for example, in an article by L. Corben, C. Bloom, D.Willoughby and A. Shepp in Journal of Photographic Science, vol. 14, No.6, 1966, pages 297-303.

A typical monobath composition for developing and fixing a stable silverimage in an exposed photosensitive element containing a silver saltemulsion according to the invention comprises an aqueous solution of (a)a stabilizing amount of a mercapto carboxylic acid or mercapto alkanolsilver salt stabilizing agent, (b) a silver salt developing agent of thegeneral formula:

wherein R is an alkylene or arylene radical containing '1 to 20 carbonatoms and Y is hydroxyl or carboxyl, and (c) an organic activator.

Monobath compositions within the scope of the invention can be preparedin any suitable manner. For example, the individual components of themonobath can be prepared prior to preparation of the monobathcomposition and mixed in an aqueous solvent before use or can beprepared in the monobath in situ. One especially suitable methodcomprises:

(1) adding a mercapton silver salt stabilizing agent to an aqueoussolvent, e.g. dissolving a mercapto carboxylic acid silver saltstabilizing agent in water,

(2) adding a p-benzoquinone, i.e. a p-benzoquinone corresponding to thehydroquinone moiety of the described hydroquinone silver salt developingagent in an amount which is less than the stoichiometric quantityrequired to react with the mercaptan silver salt stabilizing agent,

(3) adding a development activator, typically an inorganic alkali, suchas sodium hydroxide, potassium hydroxide or lithium hydroxide, to theaqueous solvent in suflicient quantity that the resulting solution isalkaline, and

(4) adding a mercaptan silver salt stabilizing agent, e.g. the mercaptocarboxylic acid silver salt stabilizing agent of step 1.

The process need not be carried out in the respective order of steps 1to 4. For example, the p-benzoquinone can be dissolved in or otherwiseadded to the aqueous solvent and then the mercaptan silver saltstabilizing agent added to the resulting solution before adding thedevelopment activator, or the development activator can be added to theaqueous solvent before the other compo nents are added.

A typical aqueous monobath of the invention is prepared by firstdissolving a mercapto carboxylic acid in water. The pH of the resultingsolution is usually below 6.0. p-Benzoquinone is then added withstirring in the ratio of 1 mole of p-benzoquinone to about 1.2 to about1.5 moles of mercapto carboxylic acid. Suflicient water is employed todissolve both of these components. Inorganic alkali, e.g. sodiumhydroxide, is added until the pH of the solution is at least about 9.0,e.g. preferably 10.0 to about 13.0. Additional stabilizing agent is thenadded, typically more mercapto carboxylic acid. Usually a buffer, suchas Z-aminoethanol, and a preservative, such as sodium sulfite, are thenadded followed by dilution of the monobath to the desired volume withwater.

The process of preparing a monobath composition of the invention can becarried out under any suitable reaction conditions of temperature,pressure and the like. Typically, a monobath is prepared under ambientconditions, especially at room temperature, pressure, etc.

The hydroquinone silver salt developing agent having at least one SRYradical as described can be prepared before addition to the monobathcomposition of the invention. These compounds can be prepared by mixingthe corresponding p-benzoquinone with a compound of the formula HS--RYwherein R and Y are as described, typically in an aqueous solvent. Anysuitable reaction conditions can be employed, but in general thereaction can be carried out under ambient conditions. The p-benzoquinonecompound and HSRY compound are typically mixed in stoichiometricquantities but mixtures outside these quantities can be employed. Theresulting compounds can be separated from the aqueous solvent beforeaddition to the monobath composition of the invention or the compoundscan be added to the monobath with the aqueous solvent.

Any suitable p-benzoquinone compound can be employed for the preparationof the described hydroquinone silver salt developing agents includingp-benzoquinone and 2-methyl-p-benzoquinone.

Another embodiment of the invention is a monobath process comprisingdeveloping and fixing a silver image in an exposed photosensitiveelement containing a silver salt emulsion layer with a monobathcomposition comprising: l

(a) a mercapto silver salt stabilizing agent,

(b) a hydroquinone silver salt developing agent having at least one SRYradical wherein R is alkylene or arylene and Y is a water solubilizinggroup, and

(c) a development activator.

The hydroquinone silver salt developing agent typical- 1y has thedescribed general Formula A and/ or the mercapto silver salt stabilizingagent is a mercapto carboxylic acid and/ or a mercapto alkanol.

The monobath compositions and processes of the invention are suitablefor developing and fixing a wide variety of photosensitive emulsions,especially silver halide gelatino photosensitive emulsions. Thephotosensitive emulsions which can be developed and fixed with thecompositions and processes of the invention include those which arenon-spectrally sensitized, such as x-ray type emulsions, or emulsionswhich are orthochromatic, panchromatic, infrared sensitive, and thelike, containing spectral sensitizing dyes such as described in US.Pats. 2,526,632 and 2,503,776. Spectral sensitizers which can be used ina photosensitive emulsion processed according to the invention includecyanines, merocyanines, styryls, and the like.

The photographic elements employed in the practice of the invention canbe sensitized by using any of the well known techniques used in emulsionmaking, e.g. by digesting with naturally active gelatin or varioussulfur, selenium, noble metal and/or gold compounds. The photosensitiveemulsions employed in the practice of the invention, as well as themonobath compositions of the invention, can contain various photographicaddenda, especially those known to be beneficial in photographiccompositions. The types of addenda and amounts to be employed can bedetermined by those skilled in the art. Suitable addenda include, forexample, hardeners, e.g. those set out in British Pat. 974,317; bufferswhich maintain the desired pH level including various sulfonamides andboraxes; coating aids; plasticizers; speed increasing addenda, such asquaternary ammonium salts and alkylene oxide polymers, and variousstabilizing agents, such as sodium sulfite.

Various colloids can be used alone or in combination as vehicles orbinding agents where one is used in the photosensitive emulsions andelements employed in the practice of the invention. Among such materialsare the natural and/or synthetic binding materials generally employedfor this purpose including, for example, gelatin, colloidal albumin,water soluble vinyl polymers, mono and polysaccharides, cellulosederivatives, proteins, water soluble polyacrylamides,polyvinylpyrrolidone and the like. In addition to the hydrophiliccolloids, the vehicle or binding agents can contain dispersedpolymerized vinyl compounds, particularly those which increase thedimensional stability of photographic materials. Suitable syntheticpolymers of this type include water insoluble polyrmers of alkylacrylates and methacrylates, acrylic acid, sulfoalkyl acrylates ormethacrylates and the like.

The silver salts processed according to the invention include any of thephotosensitive silver salts, such as any of the photosensitive silverhalides. Suitable silver halides include, for example, silver bromide,silver iodide, silver chloride or mixed halides, such as silverchlorobromide, silver bromoiodide, and the like. Preferred silverhalides are those in which the halide comprises at least 50 mole percentchloride. The silver halides used can be those which form latent imagespredominantly on the surface of the silver halide grains or those whichform latent images inside the silver halide crystals, such as describedin US. Pat. 2,592,250 of Davey and Knott, issued Apr. 8, 1952, as wellas direct positive emulsions such as those described in US. Pat.2,541,472 of Kendall and Hill, issued Feb. 13, 1951.

The photosensitive emulsions processed according to the invention can becoated on a wide variety of supports. Typical supports include thosegenerally employed for photographic elements, including various films,such as cellulose acetate films, cellulose nitrate films, polyethyleneterephthalate films, or other polyester films, polycarbonate films andrelated materials, papers, such as paper supports coated with resinousmaterials, e.g. coated with polyethylene, polypropylene and/orpolyethylenebutene copolymers, glass, metal, and the like.

In some cases it may be desirable to include morpholine or anaminoalkanol in the monobath compositions of the invention. Theseinclude any suitable aminoalkanols which have one, two or more hydroxyradicals. Suitable aminoalkanols include compounds within the formula:

wherein R is a hydroxyalkyl radical such as one containing up to tencarbon atoms, for example, hydroxyethyl, hydroxypropyl, hydroxybutyl,hydroxyisobutyl, dihydroxylpropyl, dihydroxbutyl, and the like, R and Rare each selected from the group consisting of hydrogen atoms and alkylradicals, such as those containing up to about ten carbon atoms, such asmethyl, ethyl, propyl, butyl, isobutyl, and isopropyl radicals. Suitableaminoalkanols which can be described as hydroxyalkylamines include:

Z-aminoethanol 2-methylaminoethanol 2-ethylaminoethanol2-n-propylaminoethano1 Z-dimethylaminoethanol Z-diethylaminoethanoldiethanolamine (2,2'-iminodiethanol) 2-aminopropanol 3-aminopropanol3-diethylamino-1propanol l-dimethylamino-2-propanol3dimethylamino-l,2-propane diol 4-aminobutanol 4-diethanolaminobutanolS-aminopentanol 5diethanolamino-2-pentanol 2-isopropylaminoethanol2-amino-a-methyl-l-propanol triethanolamine S-diethanolaminopentanolmethylolamine trimethylolamine 2- (di-n-propyl) aminoethanol3-methylaminopropanol 2-methylolaminoetl1anol Any suitable amount of theaminoalkanol can be employed, usually about 1% to about 30% by weight ofthe total monobath composition being used.

A silver salt developing agent, the same as or difierent from thedescribed silver salt developing agent, can be present in thephotosensitive element employed in the practice of the invention. Suchdeveloping agents include any silver halide developing agent which iscompatible with the components of the element and does not adverselyaffect the developing and fixing action of the monobath composition ofthe invention.

Suitable developing agents which can be employed include, for example,polyhydroxy benzenes, such as hydroquinone developing agents, e.g.hydroquinone, alkyl substituted hydroquinone, such ast-butylhydroquinone, methylhydroquinone, dimethylhydroquinone; catecholand pyragollol; chloro substituted hydroquinones, such aschlorohydroquinone, or dichlorohydroquinone; alkoxy substitutedhydroquinone, such as methoxy or ethoxy hydroquinone; aminophenoldeveloping agents, such as N-methyl-p-aminophenol and2,4-diaminophenols; ascorbic acid developing agents; pyrazolidonedeveloping agents, including those described in British Pat. 958,678 andBritish Pat. 930,572; acyl derivatives of p-aminophenol. Such developingagents can be used alone or in combination. It is especially desirablethat the developing agents employed in the developer compositions besoluble in water.

The concentration of developing agent in the photosensitive elementemployed in the practice of the invention can vary over a wide rangedepending on many factors, such as the desired image, the components ofthe monobath composition, and the like. It can be the major developerused in the developing and fixing process of the invention or it can bean auxiliary developing agent.

It can be advantageous in some cases to have an antifoggant present inthe monobath composition and/or in the photosensitive element employedin the practice of the invention. Suitable antifoggants include organicantifoggants, such as benzotriazole, benzimidazole,Z-mercaptobenzirnidazole and mercaptotetrazole antifoggants. Inorganicantifoggants, including potassium bromide, potassium iodide and/orsodium bromide, can be employed in the photosensitive element and/ormonobath composition of the invention. Any suitable amount ofantifoggant can be employed, depending on the components of the monobathcomposition, the photosensitive element, and the like.

Developing and fixing according to the practice of the invention can becarried out under any suitable conditions, usually ambient conditions,e.g. about 20 C. to about 30 C. However, higher temperatures can beemployed if desired.

The time for processing employing the monobath composition of theinvention can vary from about a second to several minutes or moredepending on the desired image, processing conditions and the like.

The components of the monobath compositions of the invention can bestored in one or more separate containers such as in separate packets orbottles as part of a kit before use. At the time of use the componentscan be mixed together and/or diluted to the desired concentration. Forexample, the developing agent can be in one container and thestabilizing agent in another. The two compositions can be mixed beforeuse.

The invention is further illustrated in the following examples.

EXAMPLE 1 This example illustrates preparation of a monobath accordingto the invention.

One hundred grams of mercaptosuccinic acid are dissolved in 600 cc. ofwater. Thirty cubic centimeters of an aqueous sodium hydroxide solutioncontaining 40% by weight NaOH is added. Thirty grams of p-benzoquinoneis then added slowly to the solution with agitation, the pH of thesolution being below about 6.0. The solution is clear and only slightlyyellow. An additional 35 grams of mercaptosuccinic acid is then addedand then an aqueous solution of 40% by weight NaOH and water are addedto bring the volume to 1 liter and the pH to about 1010.5. This monobathcan be employed for developing and fixing an exposed photographic silverhalide emulsion.

EXAMPLE 2 This example illustrates developing and stabilizing aphotosensitive element with a monobath composition of the invention.

An exposed photographic paper having a medium grain silver chlorideemulsion layer containing 1-phenyl-3-pyrazolidone as an incorporateddeveloping agent at the rate of 1 mole of developing agent per mole ofsilver in the emulsion is developed and fixed by immersing in a monobathprepared as in Example 1. However, 50.0 grams of anhydrous sodiumsulfite and 25.0 cc. of Z-aminoethanol are added to the monobath beforethe final dilution with water.

A stable image is developed and stabilized in the silver chlorideemulsion layer within 6 seconds at about 20 C. Similar results areobtained when the compounds 2-(2,5 dihydroxyphenylthio)ethanol, onIhydroxy 18 (2,5 dihydroxyphenylthio)propanol, 2,5dihydroxyphenylthioacetic acid, 13-(2,5-dihydroxyphenylthio)propionicacid, a-(2,5-dihydroxyphenylthio) propionic acid,2,5-dihydroxyphenylthiosuccinic acid, o-(2,5 dihydroxyphenylthio)benzoic acid, a-(2,5 dihydroxyphenylthio)-u-mercaptoadipic acid, and ed-bis(2,5-dihydroxyphenylthio)adipic acid are employed in the monobathsof this example.

EXAMPLE 3 This example illustrates preparation of a monobath accordingto the invention.

Thirty-five grams of thiolactic acid is added to 280 cc. of water.Thirty grams of p-benzoquinone and 300.0 cc. of water are added withstirring to the resulting solution. Eighty-eight grams ofmercaptosuccinic acid is then added with 200 cc. of aqueous sodiumhydroxide solution containing 40% by weight NaOH. Finally, 50.0 grams ofam hydrous sodium sulfite, 25.0 cc. of Z-aminoethanol, and sufficientwater are added to make 1 liter of solution.

An exposed medium grain silver chloride photographic emulsion isdeveloped and stabilized within 6 seconds at about 20 C. in thismonobath. The monobath is resistant to aerial oxidation also.

EXAMPLE 4 This is a comparative example illustrating advantages of amonobath of the invention over a monobath containing hydroquinone as thedeveloping agent.

A mercaptan monobath is prepared having the following composition:

Mercaptosuccinic acid: 70.0 grams.

Sodium hydroxide (aqueous solution containing 40% by weight NaOH): 90.0cc.

Hydroquinone: 31.0 grams.

Sodium sulfite (anhydrous): 50.0 grams.

Z-aminoethanol: 25.0 cc.

Water to make 1 liter.

This monobath has a pH of 10.2.

An identical monobath is prepared except that2,5-dihydroxyphenylthiosuccinic acid is employed in place ofhydroquinone as the developing agent.

At 20 C. each of these monobaths, upon initial preparation, develop andstabilize an image within 6 seconds in an exposed medium grain silverchloride emulsion layer on photographic paper. However, after 24 hoursof exposure to air, the stabilizing activity of the first monobath ismarkedly decreased, while the second, i.e. a monobath of the invention,shows no evidence of significantly de creasing stabilizing activity.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be 1 1 effected within the spirit and scope of theinvention as described hereinabove and as defined in the appendedclaims.

I claim:

1. A monobath composition for developing and fixing an exposedphotosensitive silver salt layer comprising:

(a) a mercaptan silver salt stabilizing agent,

(b) a hydroquinone silver salt developing agent having an -S-R-Y groupwherein R is an alkylene or arylene group and Y is a hydroxy or carboxygroup, and

(c) a development activator.

2. A monobath composition as in claim 1 wherein said hydroquinone silversalt developing agent contains at least one -S-R-Y radical wherein R isa 1 to 20 carbon atom alkylene or arylene radical.

3. A monobath composition as in claim 1 wherein said hydroquinone silversalt developing agent has the general formula wherein R is an alkyleneor arylene containing 1 to 20 carbon atoms and Y is hydroxy or carboxy.

4. A monobath composition as in claim 1 wherein said hydroquinone silversalt developing agent is:

2- (2,5 -dihydroxyphenylthio ethanol,

a-hydroxy-p- 2,5 -dihydroxyphenylthio) propanol,2,5-dihydroxyphenylthioacetic acid, p-(2,5-dihydroxyphenylthio)propionicacid,

a( 2,5 -dihydroxyphenylthio) propionic acid,2,5-dihydroxyphenylthiosuccinic acid, o-(2,5-dihydroxyphenylthio)benzoicacid, a-(2,5-dihydroxyphenylthio)-a'mercaptoadipic acid, or a,a-bis (2,5-dihydroxyphenylthio) adipic acid.

5. A monobath composition as in claim 1 wherein said mercaptan silversalt stabilizing agent is mercaptoethanol, mercaptopropanol,mercaptoacetic acid, B-mercaptopropionic acid, mercaptobenzoic acid,mercaptosuccinic acid, dimercaptoadipic acid, or a-mercaptopropionicacid.

6. A photographic process comprising developing and fixing a silverimage in an exposed photosensitive element containing an exposedphotosensitive silver salt layer with a monobath composition comprising:

(a) a mercaptan silver salt stabilizing agent,

(b) a hydroquinone silver salt developing agent having at least one-S-R-Y radical wherein R is alkylene or arylene and Y is a hydroxy orcarboxy group, and

(c) a development activator.

7. A photographic process as in claim 6 wherein said hydroquinone silversalt developing agent has the general formula wherein R is an alkyleneor arylene radical containing 1 to 20 carbon atoms and Y is a hydroxy orcarboxy group.

8. A photographic process as in claim 6 wherein said mercapto silversalt stabilizing agent is mercaptoethanol, mercaptopropanol,mercaptoacetic acid, fi-mercaptopropionic acid, mercaptobenzoic acid,mercaptosuccinic acid, dimercaptoadipic acid, or a-mercaptopropionicacid.

9. A photographic process as in claim 6 wherein said exposedphotosensitive element is developed and fixed with a monobathcomposition comprising:

(a) mercaptosuccinic acid,

(b) ,8-(2,5-dihydroxyphenylthio)succinic acid, and

(c) a development activator.

10. A photographic process as in claim 6 wherein said exposedphotosensitive element is developed and fixed with a monobathcomposition comprising:

(a) mercaptosuccinic acid and thiolactic acid,

(b) a-(2,S-dihydroxyphenylthio)propionic acid, and

(c) a development activator.

11. A photographic process as in claim 6 wherein said photosensitiveelement contains a silver halide developing agent.

12. A process for preparing a stable aqueous monobath composition fordeveloping and fixing an exposed photosensitive silver salt emulsioncomprising:

(a) a mercaptan silver salt stabilizing agent,

(b) a hydroquinone silver salt developing agent having at least one-S-R-Y radical wherein R is alkylene or arylene and Y is a carboxylicacid radical, and

(c) a development activator comprising:

(a) adding a mercapto carboxylic acid silver salt stabilizing agent toan aqueous solvent,

(b) adding a p-benzoquinone to said aqueous solvent in an amount whichis less than the stoichiometric quantity required to react with the saidmercapto carboxylic acid,

(c) adding an inorganic alkali development activator to said aqueoussolvent in sufiicient quantity that the resulting solution is alkaline,and

(d) adding a mercaptan silver salt stabilizing agent to the resultingsolution.

13. A process as in claim 12 wherein said mercaptan carboxylic acid ismercaptosuccinic acid and said mercaptan silver salt stabilizing agentis also mercaptosuccinic acid.

References Cited UNITED STATES PATENTS 2,875,048 2/1959 Haist et al96-66 2,525,532 10/1950 Dreywood 96-66 2,453,346 11/1948 Russell 96-612,614,927 10/ 1952 Broughton et al. 96-66 3,017,270 1/ 1962 Tregillus eta1. 96-61 3,033,765 5/1962 King et a1. 96-61 3,173,789 5/1965 King etal. 96-61 3,043,690 7/1962 Green et al 96-76 OTHER REFERENCES HaistMonobath Manual, Morgan & Morgan 1966, pp. 22, 23, 24, 31, 40, 41, 49

WILLIAM D. MARTIN, Primary Examiner M. SOFOCLEOUS, Assistant ExaminerU.S. Cl. X.R.

